So this may be the first time that I don't agree with Bruce Schneier (although I'm sure that it will not be the last). In an article for ZDnet UK, Bruce states, that ""I have a completely open Wi-Fi network, Firstly, I don't care if my neighbours are using my network. Secondly, I've protected my computers. Thirdly, it's polite. When people come over they can use it."
Now, I've got an open wireless network at home too - is is separate from the rest of my network, because it is polite and cool for all of my geek friends to get access while at my house. The part I don't agree with is: "I've protected my computers." What happened to defense in depth? Sure, personal firewalls, IDS/IPS, Antivirus, and all that good stuff is good, but what about those risks that you don't know about? I'm just not comfortable with putting machines that I do not control/have responsibility for on my network. A separate, appropriately firewalled and secured, sure.
[UPDATE] - Bruce Schneier Just updated his blog on this issue. I'm sure he is using really good security, including "unsavory men with bitey dogs." I wish I could deploy that kind! I think that the whole article might be a misqoute - either way, we intend it to get you to think!